Field of the Invention
The present invention relates in general to the field of information handling system power management, and more particularly to an information handling system battery charge management to support variable increased current use functions.
Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Portable information handling systems have shrunk in size as end users have sought mobile devices that provide convenient access to information on the go. One example of such portable information handling systems is the smart phone, which typically accesses information through both mobile telephone provider wireless wide area networks (WWAN) and wireless local area network (WLAN) hotspots. Mobile telephones generally support web browser and email applications so that end users can view data anywhere that WWAN or WLAN communication are available. However, mobile telephone devices tend to have small surface areas that include small displays so that reading lengthy documents tends to be inconvenient. Tablet information handling systems offer an alternative with greater surface area for larger displays and more convenient reading. Tablet information handling systems tend to have a form factor that is too large for use as a mobile telephone handset yet small enough to allow convenient mobility for the end user. Tablet information handling systems with 7, 9 or 10 inch screens generally have enough surface area for an end user to conveniently run book reading or web browsing applications.
In an effort to shrink the size of portable information handling systems, manufacturers have turned to planar housings with a display using the majority of a front surface area, and a touchscreen in the display that provides a keyboard. Generally, to keep the thickness of the planar housing to a minimum, portable information handling systems include thin lithium ion batteries that rest in the rear surface of the portable information handling system. Often, the lithium ion batteries are less-expensive “dumb” batteries that do not include microcontrollers to measure charge, discharge and other battery status indicators. Because of the limited size of portable information handling system housings, the flat batteries typically have smaller cell sizes so that battery life under heavy usage tends to be limited. Portable information handling systems tend to include aggressive power savings measures to manage battery charge life, such as automated screen dimming and relatively rapid power down into reduced power states when left unused.
Another reason for aggressively managing portable information handling system charge life is that re-charging of portable information handling system batteries is often performed with relatively low power charging devices. For instance, portable information handling systems often include only a single micro-USB connector that acts as both a synchronization tool to interact with external information handling systems and a charger that accepts a charge as defined by the USB interface specification. Although USB charging is convenient, the lower available rate of charge tends to increase charging time to bring a battery to a full charge.
One difficulty with lower charger capacities is that portable information handling systems generally must rely at times on both the charger and the battery to provide adequate power to run. For example, during system startup a current surge tends to occur as subsystems boot to life. In order to provide enough current to boot, a power manager typically draws power from both the battery and an external power source if one is available. If the battery charge is low during a cold start power-on event, then lack of battery assistance often means that the external USB power source will not have enough current to startup the portable information handling system. Generally, portable information handling system batteries must have 3% to 5% of the battery full charge state in order for the portable information handling system to boot. If a battery does not have this minimal charge reserve when the information handling system attempts to boot, the battery has to charge until the minimal charge reserve is available. As a result, if a portable information handling system battery has an inadequate charge, boot is delayed until the battery can charge to a point that supports boot. In some instances, end users are forced to wait minutes to hours before their portable information handling system will boot.
System boot is not the only power transition event that increases current draw above the external power adapter current supply limit. Other types of power state transitions can place a current burden on a system that temporarily exceeds external adapter current availability, often for variable amounts of time. For example, system updates, virus scans, streaming events, information technology “push” events, gaming application events or other display and/or processor heavy events can increase current draw with temporary spikes or even extended times. The extent of a current draw spike over the current supply capability of a system also varies depending on the system's hardware and software configurations, age and battery age. For instance, current draw may depend upon the types of physical components loaded on a particular system, such as the display type, the software image loaded on the system, the type and size of persistent and non-persistent memory (RAM, SSD or HDD), and the use of hardwired or wireless peripheral devices. As a result of the wide variance in current draw that can occur in various configurations and power transition events, even when operating in a steady state on external power, some portable information handling systems must maintain a battery reserve to ensure that adequate current remains available to draw at power up. This battery reserve is also available for other types of power transition events that exceed available external power, although the availability of adequate power reserve for other types of power transition events is generally fortuitous since amount of power consumed is variable and generally not tracked in conventional systems.